Great White Shark
Found in cool, coastal waters around the world, great whites are one of the largest predatory fish on Earth. They grow to an average of 15 feet in length, though specimens exceeding 20 feet and weighing up to 5,000 pounds have been recorded. They have slate-gray upper bodies to blend in with the rocky coastal sea floor, but they get their name from their white underbellies. They're streamlined, torpedo-shaped swimmers with powerful tails that can propel them through the water at speeds of up to 15 miles per hour. They can even leave the water completely, breaching like whales when attacking prey from underneath.
Great white sharks are known to be highly migratory, with individuals making long migrations every year. In the eastern Pacific Ocean, great whites regularly migrate between Mexico and Hawaii. In other ocean basins, individuals may migrate even longer distances. Like in many highly migratory species, the very largest individuals are female.
Highly adapted predators, their mouths are lined with up to 300 serrated, triangular teeth arranged in several rows, and they have an exceptional sense of smell to detect prey. They even have organs that can sense the tiny electromagnetic fields generated by animals. Their prey includes other sharks, crustaceans, molluscs, and sea birds. Larger whtie sharks will also prey on sea lions, seals, and small toothed whales like orcas. The species has even been seen feeding on dead whales.
The novel Jaws by Peter Benchley and its subsequent film adaptation by Steven Spielberg depicted the great white shark as a ferocious man-eater. Humans are not the preferred prey of the great white shark, but the great white is nevertheless responsible for the largest number of reported and identified fatal unprovoked shark attacks on humans.
The whale shark is a slow-moving, filter-feeding carpet shark and the largest known extant fish species. The whale shark is found in open waters of the tropical oceans and is rarely found in water below 21 °C (70 °F). Studies looking at vertebral growth bands and the growth rates of free-swimming sharks have estimated whale shark lifespans at 80–130 years.
In order to eat, this beast juts out its formidably sized jaws and passively filters everything in its path. The mechanism is theorized to be a technique called “cross-flow filtration,” similar to some bony fish and baleen whales. They feed almost exclusively on plankton and small fishes, and pose no threat to humans.
The whale shark's flattened head sports a blunt snout above its mouth with short barbels protruding from its nostrils. Its back and sides are gray to brown with white spots among pale vertical and horizontal stripes, and its belly is white. Its two dorsal fins are set rearward on its body, which ends in a large dual-lobbed caudal fin (or tail).
Although massive, whale sharks are docile fish and sometimes allow swimmers to hitch a ride. They are currently listed as a vulnerable species; however, they continue to be hunted in parts of Asia, such as the Philippines.
Tiger sharks are named for the dark, vertical stripes found mainly on juveniles. As these sharks mature, the lines begin to fade and almost disappear.
The tiger shark is a solitary, mostly nocturnal hunter. It is notable for having the widest food spectrum of all sharks, with a range of prey that includes crustaceans, fish, seals, birds, squid, turtles, sea snakes, dolphins, and even other smaller sharks. It also has a reputation as a "garbage eater", consuming a variety of inedible, man-made objects that linger in its stomach. Though apex predators, tiger sharks are sometimes taken as prey by groups of killer whales.
Also, they have a reputation as man-eaters. They are second only to great whites in attacking people. But because they have a near completely undiscerning palate, they are not likely to swim away after biting a human, as great whites frequently do.
Unfortunately, tiger sharks are regularly hunted—mainly for their fins, but also for their liver oil. Since they have a low reproduction rate, overfishing is a major threat to tiger shark populations. Juveniles are often caught unintentionally as bycatch, which is detrimental to the next generation. The decreasing population of tiger sharks has led the IUCN to list the species as near threatened.
The great hammerhead shark is the largest of all hammerhead species, reaching a maximum known length of 20 feet (6.1 m)1 and weight of 991 pounds (450 kg).2. The species is distinguished from other hammerheads by its nearly straight hammer-shaped head (cephalofoil) that has a prominent indentation in the middle.
Great hammerhead sharks are apex predators and can be found worldwide in coastal, warm waters that are 68 degrees (20 degrees Celsius) or higher. Unlike scalloped hammerhead sharks, great hammerhead sharks are solitary and migrate long distances upward of 756 miles (1,200 km) alone.
Their wide-set eyes give them a better visual range than most other sharks. And by spreading their highly specialized sensory organs over their wide, mallet-shaped head, they can more thoroughly scan the ocean for food.
One group of sensory organs is the ampullae of Lorenzini, which allows sharks to detect, among other things, the electrical fields created by prey animals. The hammerhead's increased ampullae sensitivity allows it to find its favorite meal, stingrays, which usually bury themselves under the sand.
Although potentially dangerous, the great hammerhead rarely attacks humans. It sometimes behaves inquisitively toward divers and should be treated with respect.
This shark is heavily fished for its large fins, which are extremely valuable on the Asian market as the main ingredient of shark fin soup. As a result, great hammerhead populations are declining substantially worldwide, and it has been assessed as Critically Endangered by the International Union for Conservation of Nature (IUCN) as of 2019.
Blue sharks are curious, open-ocean predators that live throughout the global ocean, from the tropics to cold temperate waters. They spend most of their lives far from the coast and are truly a pelagic species. The common name comes from the blue color of the skin, unique among the sharks.
Blue sharks are known to be highly migratory, with individuals making several trips across entire ocean basins throughout their lifetimes. Experts believe that blue sharks use their large pectoral fins (horizontal fins growing out from either side of the body) to ride long currents, conserving energy as they migrate. Blue sharks go on these long migrations to reach areas of dense food resources and to find potential mates. For most of the year, males and females of this species live in different places. Only during the mating season do they come together, briefly, and reproduce via internal fertilization. They are viviparous and are noted for large litters of 25 to over 100 pups.
They feed primarily on small fish and squid, although they can take larger prey.
The blue shark is relatively unaggressive but is very curious and will approach divers and spearfishers, especially if food is available. According to the ISAF, the blue shark is responsible for thirteen unprovoked shark bites worldwide.
Maximum lifespan is still unknown, but it is believed that they can live up to 20 years.
The zebra shark is a large, distinctive shark that lives in shallow coral reef habitats in tropical waters where they can wriggle into narrow crevices and caves in search of food. Its appearance, which changes as the shark reaches maturity, has caused confusion among divers who often mistake it for the leopard shark. While the zebra sharks are born dark brown with yellowish stripes, as they reach adulthood, they shed their stripes for small black dots against a tan body, closely resembling the leopard species.
They are nocturnal and spend most of the day resting motionless on the seafloor. At night, they actively hunt for molluscs, crustaceans, small bony fishes, and possibly sea snakes inside holes and crevices in the reef.
The zebra shark is oviparous: females produce several dozen large egg capsules, which they anchor to underwater structures via adhesive tendrils.
They are generally harmless to humans however, they may bite if provoked. There has been one documented unprovoked attack on a human according to the International Shark Attack File, however, this attack resulted in no injuries.
The zebra shark is taken by a wide range of inshore fisheries and prized for its meat, which may be sold fresh or salt-dried in markets throughout Indonesia, Thailand, Malaysia, Philippines, and elsewhere. Its liver is also processed for vitamins and its fins are chopped off for use in shark fin soup that remains a traditional Chinese delicacy. Although the practice of shark finning is illegal in U.S. waters, fins can still be bought and sold from unsustainable foreign fisheries, which are lacking or have ineffective shark finning bans. The combination of these practices is driving down zebra shark populations in most of their range, and they are considered endangered by the IUCN Red List. However, in Australia, the species is considered of Least Concern because it has a wide distribution and is not heavily fished.